Scientists at the University of East Anglia, UK, have detected four new man-made chemicals in the atmosphere which can attack the ozone layer. They consist of three chlorofluorocarbons (CFCs) and one hydrochlorofluorocarbon (HCFC) and they supplement the seven CFCs and six HCFCs that are already known to deplete Earth’s protective ozone belt.

The chemicals were discovered in two geographically distant regions, which helps to support their detection as described in Nature Geoscience. Firstly, archived, unpolluted air samples collected over Tasmania from 1978-2012 were found to contain CFCl2CFCl2 (also known as CFC-112), CF2ClCCl3 (CFC-112a), CF3CCl3 (CFC-113a ) and CF3CH2Cl (HCFC-133a) following GC/MS analysis.

Then the same four compounds were also found in the air released from polar firn snow from Greenland, which holds a record of the atmospheric composition over the last 100 years. The fact that the four compounds did not show up until the 1960 snow layers strongly suggests that they are man-made.

The research team estimated that a combined total of 74,000 tonnes of the chemicals had been released to date. This is far lower than peak levels of the CFCs which reached about one million tonnes per annum in the 1980s. However, they are slow to degrade in the atmosphere and the concentrations of two of them, CFC-113a and HCFC-133a, are still on the increase. So, their effects will be felt for some time to come.

"The identification of these four new gases is very worrying as they will contribute to the destruction of the ozone layer. We don't know where the new gases are being emitted from and this should be investigated. Possible sources include feedstock chemicals for insecticide production and solvents for cleaning electronic components," said lead researcher Johannes Laube. T

he compounds are all covered by The Montreal Protocol, which restricted production and use of CFCs from 1989 and banned them from 2010. The team suggested that "to ensure the long-term efficacy of the Montreal Protocol it might be worth reconsidering its reporting regime."